The present invention relates to disc drive storage systems and, in particular, to a disc drive storage system having a serial preamplifier interface with broadcast mode addressing for enabling multiple preamplifiers individually and simultaneously.
Disc drives of the "Winchester" type are well known in the industry. Such drives use rigid discs coated with a magnetizable medium for storage of digital information in a plurality of circular, concentric data tracks. The discs are mounted in a pack on a spindle motor which causes the discs to spin and the surfaces of the discs to pass under respective hydrodynamic (e.q. air) bearing disc head sliders. The sliders carry transducers known as heads which read information from and write information to the respective disc surfaces through one or more read and write preamplifiers. High storage capacity disc drives typically have a large number of heads and thus have multiple read and write preamplifiers. Each read and write preamplifier drives a plurality of individual heads, typically on a multiplexed basis.
An actuator mechanism moves the heads from track to track across the surfaces of the discs under control of a drive controller located within the disc drive. The actuator mechanism includes a track accessing arm and a suspension for each head gimbal assembly. The drive controller positions the heads based on address information received from a host processor and servo information that is written on the disc surfaces.
The servo information is written on the disc surfaces during manufacture of the disc drive. With high volume production, it is desirable to reduce the number of disc revolutions that is required to write the servo information onto the disc pack since added revolutions directly translate to added time in the manufacturing process. One method used for reducing the number of revolutions is to read and write with all of the preamplifiers simultaneously. In this method, each preamplifier has its own set of serial interface control inputs and its own set of read and write signal wires. This adds pins and signal wires to the printed circuit board (PCB) interface connector and the flex cable which are coupled between the disc drive electronics and the actuator assembly, where space is already an issue. Another difficulty with adding pins and signal wires to the disc drive is that it increases susceptibility to noise. Therefore, it is very undesirable to add pins or signal wires within the disc drive assembly. The present invention provides a solution to this and other problems, and offers other advantages over the prior art.